Brush for electrical apparatus and method of making same



A ril 15, 1924. 1,490,307 4 o. E. BECKER BRUSH FOR ELECTRICAL APPARATUS AND METHOD OF MAKING SAME Filed Nov. 7, 1921 Patented Apr. 15, 1924.

omrrosT-A E PATENT OFFICE."

OLIVER E. BECKER, OF CHICAGO, ILLINOIS, ASSIGNOR TO BECKER BROS, OF CHICAGO,

' ILLINOIS, A CORPORATION OF ILLINOIS.

BRUSH ron ELECTRICAL APPARATUS AND METHOD or MAKINGYSAME.

Application filed November 7, 1921. 7 Serial No. 513,245.

To all whom it may concern: p

Be it knownthat I, OLIVER 'E. BECKER, a citizen of the United States, residing at Chicage, in the county of Cook and State of Illinois," have invented a certain new and useful Improvement in Brushes for 'Electri cal Apparatus and Methods of Making Same, of which the following'is a full, clear, .o

concise, and exact description, reference be- 10,v ing had to the accompanying drawings forminga part of this specification; My invention relates to brushes for elec Itrical apparatus 5 and method of making same; 7

"In'cOnVeyin'g current to or from an armatureor other moving member, for example,the circuit is through a relatively sta-' tionary terminal, such as a brush having- I electrical contact with a relatively moving terminal or surface, such as a commutator,

collector ring, or the like. Flexible leaders or pig tails are usually employed to carry the current between the brush andthe cables or other conductors employed for conveying current to the apparatus; Y

The successful operation of-electrical machinery of this class *is "dependent largely .upon the electrical connection provided be tween the leaders .or'pig tails and the rela -30 tively stationary terminal or brush andthe electrical contact maintained between the relatively stationary and movable terminals. In my co-pending application, Serial N0. 483,207 filed1July -8', 1921, I have disclosed as a leader or pig tail adapted to be threaded i or otherwise inserted into the body of the brush. The outer end of the" terminal sleeve, disclosed in the above application,

is provided with" a non-circular "portion for 1 tool. The connection disclosed in my above 7 application is an improvement upon, fprovides better electrical contact and otherwise functions more satisfactorily than the prior tween. This is particularly where there engagement by a wrench or other suitable art provisions. However," I find that in some instances, engagement of that portion sibility of such difficulty by the provision of an improved lead construction and method of making the same and an imrovedcon nection between it and the brush ody.

A further feature of my present invention is the provision of an improved facing piece engageable by the means provided for pressing the brush into contact with the commutator, slip ring or the like and an improved arrangement and mounting thereof.

Still further features of my invention are "the, provision of means for still further i1nproving the electrical contact between the brush or contact piece and the lead or pig tail; for lubricating the connection between the lead and contact piece, and for preventing oxidation andkeeping the co-operating contact surfaces clean.

The result of these features, together with certain "constructural details and such other features ,as willappear from the following detailed description is a novel, simple and improved brush having structural superioritg,jmanufacturing economy and functional a vantage over the brushes of the prior art.

In order to more fully acquaint those skilled-in the art with thenature of my invention, I shall now describe, with the aid of the accompanying drawings, the steps which [I perform and the structure of the brush secured thereby; Infthe drawings: Ii igure ,1 is an elevational view of the pig tai o Figure 2 is an elevational view of the terminal sleeve or ferrule;

Figure ,3 is an elevational view of the .pig tail showing the sleeve or ferrule secured thereupon and the faces formed in the fersuitable' tool; v V

'Figure his an elevational view of the finished pig tail; Figure 5 "is avhorizontal sectional view taken substantially on the line 55 of Fig ure 4; V o Figures 6, 'Z, 8 and 9 are isometric views rule for engagement by a 'wrench or other of the brush pig tail, facing clip and the pin for securing the pig tail in the brush body respectively;

Figure 10 is an isometric view of the finished brush;

Figure 11 is an isometric view of a brush holder showing a brush embodying my invention mounted therein; and

Figure 12 is an enlarged transverse sectional view showing the manner in which the electrical contact between the contact piece and lead may be still further improved, the connection therebetn' een lubricated; oxidation prevented and the cooperating contact surfaces kept clean.

According to my invention, the end of the pig tail 10 is inserted in the sleeve or ferrule 11 and union betweenthe sleeve and pig tail then produced bydeforniing the sleeve as by crushing or pressing it inwardly to a smaller diameter between suitable dies to compress the fibres of the pig tail and firmly grip them in the sleeve.

The outer end of the sleeve 11 is pressed,

crushed or otherwise formed into a noncircular shape, so that it may be engaged by a wrench or other suitable tool. In the particular embodiment selected for -illustration. this end is shown at 12 as being formed square. It maybe formed with any desired number of faces. The faces 12 may be formed simultaneous with the effecting of the gripping action or union between the sleeve 11 and pig tail 10, or they may be formed in independent steps if so desired. It should be noted, however, that the periphery of the squared end 12 is confined wholly within the diameter of the lower portion 13 of the sleeve or ferrule. V L

Screw threads 14 are then formed preferably throughout the length of the sleeve 11 as shown. continuing up through the corners 15 of 'the squared end 12 of the sleeve. Should the end 12 squared to a dimension within theinternal diameter of the threads 14, the threads will, of course, not take in the corners The threads 14 are preferably formed by rolling as in my co-pending application, not only because such a method is cheaper, but because such method of forming the threads tends to increase rather than decrease the gripping action or union between thesleeve and the strands of the pig tail. Vhile the end of the sleeve 11 is preferably squared first and the screw threads 14 then formed therein described. it is to be un'derstood that these steps in forming the pig tail may be reversed and the sleeve 11 threaded first and one end then squared without departing from my present invention.

The threads formed should preferably be sharp 60 threads to secure a large contact area withthe material of the brush.

The threaded end of the sleeve or ferrule of the finished pig tail is then screwed into an opening 16 in the brush body 17. Vhile the particular brush shown is of the rigid granular type composed usually of a carbon base, such as graphite or coke mixed with other ingredients to impart structural strength and good wearing qualities, it is to be understood that my present invention is not limited to any particular type of brush. The opening 16 in the brush body 17 may be tapped as shown, or the inner end of the sleeve 11 may be fluted and thereby screwed into the opening 16 without tapping the same as described in my co-pending application. In either event, the connection established between the pig tail and the brush possesses the mechanical requirements of strength and durability and the electrical requirement as to firm contact over a large area is maintained, even after prolonged service. It should be noted that the pig tail may be screwed completely and securely into the brush without in the least impairing the firm contact between the threads on the sleeve 11 and those in the opening 16, such as might happen under certain conditions where the insertion of the pig tail is limited by engagement of a shoulder or enlarged portion on the sleeve 11 with the brush body.

Upon complete insertion of the pig tail, an opening is drilled or otherwise formed transversely through the brush body 17, sleeve 11 and the end of the pig tail strands secured therein and a pin 18 is then inserted through this opening and riveted or headed over at its opposite ends to securely bindthe pig tail and its terminal sleeve in the body of the brush. I

Intermediate the opposite ends of its upper edges, each of the opposite faces of the brush body 17 is scarfed or notched as shown at 19 to receive the downwardly converging flaps or cars 20 of a facing clip 21.

The scarfs or notches 19 are under-cut as shown in Figure 6, that is, they extend deeper into the body of the brush at a point below the upper edge than they do at the upper edge. The facing clip 21 which is made up of suitable spring stock, preferably phosphor bronze is secured in place by spreading the downwardly converging flaps or ears 20 and springing them into the under-cut notches or scarfs 19 as shown in Fig. 10. Vhen so positioned, that portion of the clip 21 connecting the flaps QOcxtends transversely across the upper surface of the brush body providing an admirable facing surface engageable by the means provided for pressing the brush into contact with the commutator or slip ring.

The facing clip 21, particularly the under surface. which comes into direct engagement with the brush body, is provided with a suitable insulating coating. I find that two I coats oftjapani, provides a-xhighlysatisfactory coating for. this purpose.- Instead of coatingthe facing piece a layer, of paper or other suitable insulation maybe arranged between itand thebrush body 17. Ineither case, the'pig tail'makes direct electrical.

contact with the brush body entirely independent of thcmechanical connection provided between the facing piece and the .brush. Consequently, the variable electrical contact I and accompanying variable resistances {heretofore encountered,

especially where the mechanical connection between the facing piece andbrush has Served as the electrical connection between the leader or pigtail and the brush are avoided, and a ..(-onstant, contact resistance is provided.

F urthermofre, there is no possibilityfof a I I flow of currentbeing' setup to the brush 2o brush intocontact with the commutator or through the arm provided for pressing the slip ring and facing piece engaged thereby as has been ossibleheretofore, especially where the lea er I or pig tail has beenelectrically connected at oneend. with the facing piece at the brush and at its opposite end flwith: awmetallic arm or terminal carrying the spring pressed arm. 1

In Fig. 11, I have illustrated the manner in which a brush embodying my inventionmay be mounted in the usual brush holder employed in apparatus with which such brushes are adapted for use. The details of the holder per so are, of course, immaterial in so far as m present invention is concerned, and wil vary in different machines. The particular holder shown comprises an open rectangular frame 25 having an arm 26 terminating at its free end in a clam ing jaw 27. The arm 26 carries a plate 28 aving upturned bearings 29. which support a shaft 30. Onebearing is provided with a plurality of ratchet teeth for engaging the end 32 of a spring 33coiled about the shaft good contact between the brush and collector ring or commutator.

The elimination of an enlarged portion beyond the threads formed in the terminal sleeve insures proper electrical contact regardless of how securely the terminal is forced into place. Threadingof the sleeve is also facilitated.

In Figure 12 I have shown the manner in which the electrical contact between the con- ,tact piece andlead may be still further improved, th e;.connection therebetween lubricated, oxidation prevented and the cooperating contact surfaces kept clean. In this case the opening 16 in the contact piece or brush body 17 is tapped to receive the threaded end 14 of the leadlO'. The tapped openin v16 is filled about two-thirds full of a con ucting powder 50 preferably Ceylon graphite.

The threadedend 14 of the lead is that insorted into the opening 16 and engaged with the threads therein whereupon the brush body or contact piece'isj turned upside down i and the lead then screwed up into place. I findthat the conducting powder 50 not onlylubricates the cooperating threads between the contact piece and lead, prevents oxida- 1 tion and keeps the cooperating; contactsurfaces clean, but that it forms a cushion mechanically between the lead and brush and.

forms an exceedingly good bottom contact between the end of-the lead and thebottom of the opening 16. The conducting powder upon being compressed'between the end of the lead and the bottom of the opening yields sufficiently to permit good electrical contact being made 'therethrough without distorting the contact between the cooperating threads and impairing the flow of current 'therebetween.

' While I have described my" invention in connection with a brush, it is obvious that the invention may be practiced in connection with various other contact members than the one shown, whether or not such contacts are iincluded under the term brushes.

I do not intend to be limited to the precise details shown and described, and I intend that modification in the order of practicing the various steps such as will be apparent at once to those skilled in the art are contemplated within the scope of the appended claims. 1

I claim:

1. The method of forming a pig tail which comprises, inserting a pig tail strand in a sleeve or ferrule, forming a non-circular portion in the sleeve or ferrule and forming threads in the ferrule past said non-circular portion. a i

2. The method of forming a pig tail which comprises, inserting a pig tail strand in a sleeve or ferrule and then formin threads and a non-circular portion in the t read receivinglength of the ferrule in successive steps.

3. The method of forming a pig tail which comprises inserting a pig tail strand in a sleeve or ferrule, then deforming the material of the sleeve to force it into secure engagement with the strand and then forming threads in the sleeve throughout its length.

4. In combination, a stranded conductor,

a cylindrical sleeve permanently shrunk upon one end of the conductor, said sleeve having its outer end threaded and its inner end oi' non-circular formation for enga ement bya suitable wrench and confined wit in the peripheral dimension of the threaded outer end.

. 5. In combination, a conductor, a sleeve permanently shrunk upon one end of the conductor, said sleeve being threaded and having a non-circular portion confined-w1ththreaded portion for engagement by a suitable tool. 7

7; In'combination, a conductor, and a sleeve shrunk on the end of the conductor, said sleeve having a non-elrcularportion for engagement by a suitable tooland being threaded pastsaid non-circular portion.

-8. In combination, a brush ody having a hole extendinginto but not through the a body thereof, a conductor having a sleeve of metal secured upon its end, said sleeved end i being threaded into said hole and means-interposed between the sleevedend of the conductor and-the bottom of said hole for hot toming theconductorin the hole.

: stranded conductor and threaded for engagement in the brush body, a conducting powder interposed between the end of the conductor and the bottom of the hole, and a retention element engaging the brush body and the sleeved end of the conductor for holding the same against unthreading.

11,The method of connecting a lead mechanically and electrically to a brush body which comprises, shrinking a sleeve permanently upon the end of the lead, forming threads upon said sleeve, forming an opening in the brush body, introducing a conducting powder into'said opening, and threading the sleeved end of the lead into the openingandbottoming same on said powder.

In witness whereof, I hereunto subscribe-my name this 4th day of November, 1921.

OLIVER E. BECKER. 

